The present invention relates to a tape loading device to be suitably used in a magnetic recording/reproducing apparatus such as a video tape recorder.
In recent years, a magnetic recording/reproducing apparatus such as a video tape recorder (which will be hereinafter referred to as "VTR") has been remarkably spread, and a VTR has accordingly become familiar.
In such a magnetic recording/reproducing apparatus, there is provided a known tape loading device as shown in FIGS. 8 and 9 by way of example. A schematic construction of the tape loading device as illustrated will now be described. Referring to FIGS. 8 and 9, reference numeral 1 designates a head drum having two upper and lower drum members (not shown) and a rotary head chip (not shown) provided between the upper and lower drum members so as to project in a radial direction of the head drum 1. A rail 2 is provided so as to surround the head drum 1, and it has two guide slots 2a and 2b extending along the outer circumferential surface of the head drum 1. Two guide assemblies 3 and 4 are movably mounted on the rail 2 so as to be guided by the two guide slots 2a and 2b, respectively. The guide assembly 3 on the supply side has a roller guide 3a and an inclined guide 3b for drawing a magnetic tape 6 accommodated in a tape cassette 5 and wrapping the magnetic tape 6 around the outer circumferential surface of the head drum 1. Similarly, the guide assembly 4 on the take-up side has a roller guide 4a and an inclined guide 4b for drawing the magnetic tape 6 accommodated in the tape cassette 5 and wrapping the magnetic tape 6 around the outer circumferential surface of the head drum 1.
Referring to FIG. 8, a tape travelling system in the magnetic recording/reproducing apparatus includes a pinch roller 7, capstan 8, full erasing head 9, channel erasing head 10, recording/reproducing fixed head 11, tape guide 12 as a tension regulator, tape guides 13 to 17 on the supply side, and tape guides 18 to 20 on the take-up side.
In the tape loading device as constructed above, a loading operation of the magnetic tape 6 is performed by moving the guide assemblies 3 and 4 along the guide slots 2a and 2b, respectively. That is, the guide assembly 3 on the supply side and the guide assembly 4 on the take-up side are moved in opposite directions with respect to the head drum 1, thereby drawing the magnetic tape 6 out of the tape cassette 5 and spirally wrapping the magnetic tape 6 around the outer circumferential surface of the head drum 1.
In such a tape loading device, as shown in FIG. 10, a wrapping quantity of the magnetic tape 6 around the outer circumferential surface of the head drum 1 is normally set to a sufficient wrapping quantity c obtained by adding an overwrapping quantity b to a wrapping quantity a necessary for recording and reproduction. In FIG. 10, reference character d denotes a wrapping quantity suppressing the occurrence of bouncing of a signal waveform, and reference numerals e and f denote a rotational direction of a head chip 1a and a travelling direction of the magnetic tape 6 in recording and reproduction respectively. Further, reference character O denotes the center of the head drum 1.
However, the prior art tape loading device does not have a function of adjusting a wrapping quantity of the magnetic tape 6 around the outer circumferential surface of the head drum 1. Accordingly, even when the magnetic tape 6 is overwrapped with the quantity c around the outer circumferential surface of the head drum 1, there occurs a problem such that as shown in FIG. 11, an upper edge 6a and a lower edge 6b of the magnetic tape 6 at opposite wrapping end portions A and B shown in FIG. 10 enter a circumferential groove 1b of the head drum 1 or approach the same as close as possible, owing to the structure of the head drum 1, causing a reduction in contact pressure of the magnetic tape 6 against the head drum 1 at the portions A and B under the influence of an air flow generated during rotation of the rotary head chip 1a. As a result, referring to FIG. 12, there occurs bouncing of a signal waveform at starting or ending of contact of the head chip 1a with the magnetic tape 6 at the portions A and B, so that sufficient information cannot be obtained in a region necessary for recording and reproduction.